Current automobiles typically contain supplemental inflatable restraints (air bags) located in the passenger compartment for occupant protection in the event of a crash. These vehicles also contain one or more accelerometers affixed to the vehicle body in locations at which it is desired to detect a crash impact. One or two such sensors may be located at the front of the vehicle on the radiator cross bar for early detection of front end impacts. Another acceleration sensor may be located in the passenger compartment, e.g., under a front seat. These sensors typically transmit a continuous stream of voltage signals to a crash detector control module. The control module is programed with a suitable algorithm(s) to receive the acceleration signals and to filter, store and analyze them to determine whether an impact is occurring requiring inflation of a restraint. The detection of an impact and activation of an airbag or other passenger protection device usually has to be accomplished within a tenth of a second after the initial impact.
The acceleration sensors are presently incorporated into a suitable printed circuit board for production and transmittal of the acceleration signals. The boards are oriented and mounted so that the direction of the impact force is known. Under normal vehicle operation the accelerometers experience no unusual acceleration and the control module simply cycles their baseline inputs through a data receiving and discarding mode of operation. However, the voltage outputs of each acceleration sensor contain appreciable variation from a plurality of sources and the control module must be capable of dealing with such variation in its crash analysis task.
It is an object of this invention to provide a method for the management of variations from multiple sources in acceleration sensor output. More specifically, it is an object of this invention to provide a process that will serve as a variation management tool for the calibration and validation of crash detection algorithms using accelerometer data.